I'm gravitating towards the theory that a stranger took Kyron. I don't have much in the way of evidence to support it, but I also haven't found anything to oppose it. Basically, a man came to the school, walked in with the other parents and simply acted as he belonged, until he found a kid that seemed meek and pliable. He lured him out of the school by asking him to fetch something from his car, and then drove away with Kyron. After that, well, I just hope it was fast, because I don't think Kyron is still alive.
Bold predators exist, and in this case, their advantage would be no one there recognizing them, and also no need to return to the scene of the crime. Kyron could be pretty much anywhere. If he's found, it's likely to be some distance away, like Lindsey Baum or Isabel Celis.
Timewise I think it happened not many minutes after nine, if not a few minutes before. Close enough that the general chaotic mess of the fair and unusual activity (touring the exhibits in groups) made it difficult for witnesses to give exact times.